The present invention relates to an ethylenic thermoplastic resin composition and a heavy duty bag. More particularly, it is concerned with a thermoplastic resin composition formed by a combination of three kinds of ethylenic polymers, having superior low-temperature impact resistance and moderate rigidity, and suitable as film for a heavy duty bag, as well as a heavy duty bag obtained from the said composition.
As the material for industrial-use films, particularly films for heavy duty bags to contain fertilizers, industrial chemicals, sugar, salt and soil, there has heretofore been widely used an ethylene-vinyl acetate copolymer (EVA). Since a heavy duty bag containing a heavy material may be handled very roughly during the transport work, the film of the bag is first required to be superior in impact resistance, particularly, low-temperature impact resistance. Further, in order for the bag to stand by itself during the automated filling operations, the film is required to have stiffness, namely, moderate rigidity.
Recently, for resources saving, studies have been made to reduce the film thickness of heavy duty bags to 200 .mu. or less. To this end, the resins to be used are being desired to be more excellent in the above characteristics than before.
As an example of such resources saving type heavy duty bag film, mention may be made of a linear low-density polyethylene (LLDPE) film. However, LLDPE is not always desirable because its melt tension is low and so the bubble stability is impaired during inflation molding, leading to deterioration of the film forming property. To remedy this drawback, if LLDPE is blended with a low density polyethylene (LDPE) or EVA (see, for example, Japanese Patent Laid-Open No. 225235/86), there will not be obtained a sufficient low-temperature impact resistance. Further, if an ethylene/.alpha.-olefin copolymer rubber (e.g. EPR or EPDM) is added for the purpose of improving impact resistance, the film will be deteriorated in its rigidity and so this is not desirable, either.
In view of the points mentioned above, the present invention aims at providing a novel ethylenic thermoplastic resin composition suitable as film for a heavy duty bag, and a heavy duty bag obtained from the said composition.